Marker sleeves have been known to the art for many years which comprise tubular bodies having a circular cross section and a smooth outer wall, the sleeves generally being made of a slightly elastic extruded thermoplastic material. The sleeves are especially useful for application to electrical wires for identification purposes. A marker of this type in a given size, however, generally is limited to use with a narrow size range of articles because it is often difficult to stretch it sufficiently to fit about larger diameter objects, and it can only loosely fit smaller diameter articles instead of being firmly positioned in place.
Various sleeve constructions have been developed to overcome some of the problems of the circular sleeve marker. One of these shown in the patent art, but of unknown commercial acceptance, is a sleeve having internal logitudinal V-shaped grooves, see Italian patent No. 625,732. Other forms, which have presently gained wider commercial usage, have one or more longitudinally extending convolutions or loops which are intended to allow the sleeve to be expandable, see U.S. Pat. Nos. 3,487,574 and 3,534,777. A prior art marker sleeve similar to the former patent is shown in cross section FIG. 6 and has a longitudinal groove which may be described as an inverted V-shape. Another prior art sleeve of this general type, which is also used commercially, is shown in FIG. 7 and has an upright V-shaped groove extending longitudinally of the sleeve.